Nicholas Edward Butson, 20, took responsibility for robbing two of the eight banks police say were hit by a father and his sons between May and September. (Courtesy CSPD)

A Colorado Springs man pleaded guilty Monday to playing a role in a bank robbery spree that also led to the arrests of his father and brother.

Nicholas Edward Butson, 20, took responsibility for robbing two of the eight banks police say were hit by a father and his sons between May and September. Also charged in the robbery spree were Braden Wayne Butson, 23, and Brock Edward Butson, 53.

Police believe Braden and Nicholas Butson took turns robbing the banks while their father served as a getaway driver, according to court documents released after the trio's Sept. 5 arrest. No one was injured. Police didn't disclose how much money was taken.

Nicholas Butson faces up to six years in prison under the terms of his plea agreement, his attorney, Cynthia McKedy, told the court. Sentencing is scheduled for Jan. 13 before 4th Judicial District Judge Robert Lowrey.

During a brief appearance, Butson answered the judge's questions in a soft voice, describing how he escaped with cash from the People's National Bank on May 24 and again from Academy Bank on July 20, each time after handing a teller a threatening note.

The shackled defendant said that his father, Brock, drove a getaway car both times but denied involvement by his brother.

The co-defendants have yet to enter their pleas to robbery charges. The older brother is set to appear Thursday, and the father is due in court Nov. 12, court records show.

The Butsons' arrests drew attention from national news media, including ABC News, which dubbed the crimes "a family affair." Police described a frustrating investigation in which witnesses seemed to describe the same man but gave varying height estimates, ABC news reported.

After their arrests, Braden Butson listed his height at 6-foot-2, while Nicholas Butson gave his height as 6-foot-10, jail records show.

Police cracked the case after receiving a tip from a friend of Brock Butson's longtime girlfriend, investigators disclosed in an arrest affidavit. That person recognized one of the Butsons from surveillance footage released by investigators and circulated on Facebook, the court document said.